Hyacinth is clearly trying to put the OP on the defensive, because the defensive position is always weaker. To my mind, the only solution is not to play, don't even pick up the rope and avoid the superiority dance. I had to learn this for handling a CW who plays the game in a slightly different way but the same basic "I'm the alpha" approach. Before, I noticed I ended up justifying my position for no reason other than the CW kept attacking what I was saying. But I never was able to satisfy the cross-examination because the CW's point wasn't to get a better justification, it was to keep me on the defensive. I realized, I don't need to keep responding to CW. There's no point to it, so I don't play.
I vote for bland and non-committal as the way to go. If you respond with bored disinterest, but a half-smile and brief eye contact before returning to what you were doing, that should take some of the wind out of her sails. It's like expressing that you acknowledge she spoke to you, but you're just not available for conversation at the moment (ever). After all, whatever you were doing before she spoke up has got to be more interesting than having another prickly conversation with her, right? She might consider you stand-offish, but isn't that a win?
Hyacinth: <any comment that could lead to a negative conversation>
"Hmm?" (I wasn't listening, and I don't think I missed anything)
"Oh, I don't know." (not interested in having this conversation)
"I don't remember, actually." (still not interested in having this conversation)
"Okay then." (yep, she's still talking)
"Sorry, I'm trying to focus on this." (work is calling, gotta answer)
and the classic: "So you've said."